R/C2/Introduction-to-basics-of-R/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Welcome to the spoken tutorial on basics of R. |
| 00:06 | In this tutorial, we hope to provide a feel for R and Rstudio |
| 00:11 | How can R be used as a calculator? |
| 00:14 | How to use built-in functions like sin and log? |
| 00:17 | Introduction to vector operations |
| 00:19 | Introduction to plotting |
| 00:21 | Taking help in RStudio and |
| 00:24 | Where to get more information on R and Rstudio |
| 00:28 | To understand this tutorial, one needs to know elementary maths. |
| 00:32 | For example, log, sine and plotting |
| 00:35 | Please locate this tutorial on our website, spoken tutorial dot org |
| 00:40 | We provide many useful supplementary material in this page |
| 00:44 | No programming background is required, however, to understand this tutorial |
| 00:50 | I am using version 3 of R,Using RStudio 0.97 |
| 00:56 | R and RStudio work on web browsers also |
| 01:00 | Hence, these are easily accessible from every operating system, including Aakash |
| 01:07 | Let us continue with system requirements. |
| 01:09 | For this tutorial, I am using Mac OS X 10.7.4 |
| 01:14 | But the usage is similar in Linux and Windows as well |
| 01:18 | Let us give a quick introduction to R. |
| 01:21 | R is an outstanding software for general computations |
| 01:24 | It is especially suitable for statistical computing |
| 01:27 | It is an alternative to SPSS |
| 01:30 | It is a free and open source software |
| 01:32 | It can be downloaded from c ran dot r dash project dot org |
| 01:39 | Let us now give a quick introduction to Rstudio |
| 01:42 | RStudio is a friendly front-end to R |
| 01:45 | It is a free and open source software |
| 01:48 | It can be downloaded from rstudio dot com |
| 01:51 | A two minute video by the RStudio team is available here. |
| 02:01 | Let me return to the slides. |
| 02:05 | RStudio also runs on a web browser. |
| 02:09 | Here is a screenshot of R and RStudio on a web server, accessed from Aakash |
| 02:15 | Let us do a practice session on R, using Rstudio |
| 02:21 | You now see RStudio on the screen. |
| 02:24 | I have shrunk its size quite a bit, to fit into a small screen. |
| 02:29 | Please use a size you are comfortable with. |
| 02:32 | I have also enlarged the font size, so that the recording is clear. |
| 02:36 | You do this on Windows and Linux, by pressing control and + keys together. |
| 02:41 | For this tutorial, I want to maximise the size of the console of Rstudio. |
| 02:48 | I do this by pressing the maximise button in the console window. |
| 02:54 | I also maximise the right lower window of RStudio in a similar manner. |
| 03:02 | Let me begin multiplying two numbers two point one and five. |
| 03:12 | R gives the answer in black as ten point five. |
| 03:16 | I want to divide this by three. |
| 03:18 | I will recall the previous command by clicking the up arrow. |
| 03:22 | What I typed earlier, namely two point one into five appears. |
| 03:26 | I will divide this by three to get the answer three point five. |
| 03:31 | I can add two numbers. |
| 03:35 | I can store the result in a variable using the assignment operator. |
| 03:42 | Less than symbol followed by hyphen. |
| 03:48 | One can also use an equal sign. |
| 03:53 | If I want to see what is in a variable, I just type the variable name. |
| 03:59 | In this case, I type a and see that it has five. |
| 04:03 | I will subtract zero point one six from a. |
| 04:11 | I will raise it to the power of zero point 5. |
| 04:15 | Remember, I have to put a minus zero point one six within brackets, to get the correct answer. |
| 04:26 | We get two point two, as expected. |
| 04:29 | Using the left and right arrows, I moved the cursor back and forth within a command. |
| 04:35 | I can also carry out the same calculation using the function call, square root. |
| 04:48 | I will find the value of e by using the function call, exp. |
| 04:55 | You may have noticed, the moment I open a bracket, R automatically closes it. |
| 05:01 | This eliminates errors due to unmatched brackets. So, we see the value of e above. |
| 05:08 | I can find the natural logarithm of e with the help of the log function. |
| 05:18 | The value is one, as expected |
| 05:22 | How do we find the log to the base ten? |
| 05:25 | Use the command log10. |
| 05:30 | Ten to the power five. |
| 05:36 | This gives the answer as five, as expected. |
| 05:40 | What happens if I forget the ten in log10? |
| 05:48 | We get a different answer. |
| 05:50 | It is easy to verify that this answer is correct for natural logarithm. |
| 05:54 | Can you please suggest a method to verify this? |
| 05:57 | There is another way to find the logarithm to the base of 10. |
| 06:04 | Give the base as the second parameter, as I do here. |
| 06:13 | We get five, as expected. |
| 06:16 | It is easy to create vectors in R. |
| 06:19 | z = s e q -1 comma 2 comma 0:5 |
| 06:29 | This creates a vector starting at minus one, going up to two, in increments of point five
s e q denotes sequence. |
| 06:44 | Let us see the value of z. |
| 06:48 | We will see other ways to create vectors in another tutorial. |
| 06:53 | We can calculate the length of the vector z using the command length: |
| 07:01 | We get the result seven, as expected. |
| 07:07 | We will now discuss pi. |
| 07:09 | The value of pi, is stored in the variable pi, p i, which we can see now. |
| 07:16 | Let us create a vector x to start from minus two pi, go up to plus two pi, in increments of one. |
| 07:30 | Please remember to put the multiply sign. |
| 07:34 | Let us see what x contains |
| 07:38 | Let us find the sine of this vector using sin and store it in y. |
| 07:51 | We can work directly with vectors in R, as we did above. |
| 07:56 | Let us see what y contains. |
| 08:00 | Let us plot sin(x) versus x, with type=L argument added. |
| 08:12 | Note that x comes first and then y. |
| 08:17 | This plot starts from zero as expected, because sin of minus two pi is zero. |
| 08:24 | The plot is not smooth, as there are not many points. |
| 08:28 | Let us now get more points by lowering the increment number to point one. |
| 08:41 | What happens if I try to plot without recalculating y? |
| 08:46 | R will complain that the lengths are unequal. |
| 08:52 | You should pause the video and confirm that the lengths are unequal. |
| 08:57 | Let me recalculate y. |
| 09:00 | Let me re-plot this curve. |
| 09:05 | You can see that the plot is smoother now. |
| 09:08 | Please pause the video now and look at the values stored in x and y. |
| 09:13 | Please confirm that these values are as per expectation. |
| 09:18 | We see the lengths of x and y to be 126. |
| 09:28 | You should verify that these lengths are correct. |
| 09:31 | You should also display the values of x and y and verify. |
| 09:35 | If we drop the type parameter in the previous command, we get a plot with points. |
| 09:45 | Let us press the help button in the right hand side window. |
| 09:49 | Let us type plot next to the lens symbol and hit return. |
| 09:58 | Let us scroll. |
| 10:00 | One can see different choices for the type parameter. |
| 10:04 | We have come to the end of this tutorial. |
| 10:08 | Let us see a few low cost books on R. |
| 10:17 | In this tutorial we learnt about, a few elementary operations |
| 10:22 | Introduction to plotting |
| 10:24 | Introduction to help |
| 10:26 | URLs and books on R and Rstudio |
| 10:30 | We now suggest an assignment |
| 10:32 | Find answers to log2 (2^5) and log (e^2) |
| 10:39 | Please explain your answers |
| 10:41 | Explore the Help tab in RStudio: Change the labels, title, etc. |
| 10:47 | Hint: try the plot command with x l a b argument |
| 10:53 | Copy paste a few examples provided in Help and see what they do |
| 10:58 | This video summarises the Spoken Tutorial project. |
| 11:02 | If you do not have good bandwidth, you may download and watch it. |
| 11:06 | We conduct workshops using Spoken Tutorials. |
| 11:09 | Give Certificates. |
| 11:12 | Please contact us. |
| 11:15 | The Spoken Tutorial project is funded by MHRD, Gov. of India |
| 11:22 | Thanks for joining, goodbye |
